Agriculture and Food

Foods are complex mixtures of components with diverse thermal, mechanical, rheological and ageing properties. Synchrotron techniques allow researchers to correlate the macroscopic properties of a sample with its microstructure, helping companies meet consumer demand for nutritional value, novelty and ease of use, across products ranging from bread to butter.

The food industry benefits from the advantages of synchrotron radiation in different ways. A few of the possibilities of research that the ESRF offers are:

• Visualising the multi-length scale pore structure of samples, for example, freeze-dried vegetables.
• Understanding how the microstructure of food changes due to temperature abuse using high-resolution tomography imaging.
• Detecting trace elements and map molecular groups and structures on the nanoscale using infrared spectroscopy.

Company

Challenge

Grains are a main component in the human diet and a major source of essential mineral elements. Unfortunately, many of these elements, such as magnesium, zinc or iron, for example, are tightly bound in the so-called phytate salts and the body does not easily absorb them. There are some ways of making these elements more bioavailable, namely through thermal and mechanical processing, soaking, fermentation, and germination/malting of seeds and grain. These processes enable the release of tightly bound mineral elements, especially those bound in phytate.

Among mineral elements, iron is particularly poorly bioavailable, and this is especially problematic in vegetarian diet. Researchers are now working to determine speciation and bioaccessibility of iron in processed grains in comparison to un-processed grains. Knowing only the amounts of iron in foods is not enough, researchers need to determine speciation and binding states of iron to understand the bioavailability of iron. Having great concentrations of iron is not effective if all iron is bound too strongly to be absorbed during digestion. Fortification is a costly procedure and not very efficient in the case of iron, as iron is easily reduced and can affect the taste of the produce. Promoting staple food as a good source of bioavailable iron, especially for gluten intolerant individuals (they can consume buckwheat), would be interesting for industry.

Sample

Tartary buckwheat is a gluten-free crop with great potential as a wheat substitute. It has relatively high concentration of iron, which occurs predominantly bound in phytate. The team studied the mineral element concentrations and iron speciation in grains and their processed counterparts, namely groats (hydrothermally processed grains that have the outer grain layers removed) and sprouts (7-day-old seedlings). Grains and groats of two buckwheat species were obtained from Mlin Rangus (Slovenia).

Solution

The ESRF micro-X-ray fluorescence spectroscopy’s beamline ID21 provided the spatial distribution of mineral elements and iron speciation in grains, groats and sprouts It also showed that germination affects the mineral element distribution and speciation of iron. They found that iron bioaccessibility was 4.5-fold greater for grains than groats, suggesting that iron is more bioaccessible in the outer layers of un-processed grains than in the rest of the grain. Bioaccessibility of iron in sprouts was lower than in the grains indicating that germination does not favourably affect the bioaccessibility of iron.

Benefits

This study showed that iron in the outer layers of the grain is most bioaccessible. It would be thus useful to include part of these layers in the flour and in products produced from tartary buckwheat flour to ensure greater iron intake. Iron dense products are highly desired for alleviation of iron deficiency, which occurs particularly in pregnant and breastfeeding women, children and elderly.